1. Field of Invention
This invention relates to a process of treating tannin-containing wood substrates with an aqueous solution of a polyalkylenimine and to the resulting polyalkylenimine-treated substrates.
2. Description of the Prior Art
Although various processes of inhibiting tannin migration in tannin-containing wood substrates are known, none use or suggest the use of an aqueous polyalkylenimine solution. For example, Lalk et al. U.S. Pat. No. 3,900,619 teach the application to such substrates of a water-soluble S-aryl cycloaliphatic sulfonium compound. Harren et al. U.S. Pat. No. 3,494,878 teach incorporating an ion exchange resin into an aqueous coating composition comprised of a dispersed emulsion polymer of vinyl addition type and applying same to cedar and redwood type substrates. The ion exchange resin must be highly cross-linked to prevent its leaching from the substrate.
Dickson et al. U.S. Pat. No. 3,313,736 teach many and varied uses of polyalkylenimines, among which include dyeing assistance and dye fixing. Krallmann et al. Fr. Pat. No. 1,498,727 also teach dye fixing (in fibrous material, such as cotton) with a polyalkylenimine. However, these and other polyalkylenimine references do not address the problem of tannin migration in tannin-containing wood substrates and are thus silent thereon.